To establish whether there is a link between cases of acute watery diarrhoea and a specific Aeromonas species.Eight strains studied were identified as aeromonads and were further characterized by biochemical tests, fatty acid analysis and ribotyping.Aeromonads were isolated repeatedly from stool specimens of four children under one year of age with acute diarrhoea, two of whom were admitted to hospital. Of eight isolated aeromonads strains six were identified as A. caviae, one was classified into A. veronii bv. sobria and one could not be identified to the species level. Only two A. caviae strains from one patient were found to be identical by ribotyping while the Aeromonas species (strains) isolated from the other cases differed from one another. Contaminated fresh water, contaminated food and contact with travellers with imported diarrhoea were identified as probable sources of infection.Four cases of acute gastroenteritis in small children document that aeromonads are not rare and can cause serious health problems. However, epidemiological links remain unclear. We did not prove correlation between the four serious cases of acute diarrhoea and specific Aeromonas species but the results suggest the predominant role of A. caviae.
Cilem prace bylo upozornit na možnou souvislost mezi připady
akutnich průjmových onemocněni a konkretnim druhem rodu
aeromonas. Dokumentovane ctyři připady akutnich průjmových
onemocněni malých děti ukazuji, že aeromonady nejsou vzacne a
mohou způsobovat važne zdravotni problemy. Nepodařilo se
prokazat, že klinicky zavažne připady byly spojeny s jednim
konkretnim druhem rodu aeromonas, i když výsledky naznacuji
dominantni ulohu druhu A. caviae.
Aeromonads are a new unusual pathogens, which can cause mainly
gastroenteritis as well as wound infection or septicaemia.
Identification of aeromonads to the species level is due to
ever changing taxonomy very difficult and sometimes doubtful.
Recently, three subspecies of A. hydrophila - A. hydrophila
ssp. hydrophila, A. hydrophila ssp. dhakensis and A. hydrophila
ssp. ranae have been described. Aim of the study was to prove
if the mentioned taxons can be isolated from clinical samples
and identified in routine clinical laboratory and if also A.
hydrophila ssp. dhakensis could be involved in diarrheal
diseases in our region. 138 isolates of aeromonads were
obtained in routine survey in 2003 and 2004. Biochemical
identification was done by ENTEROtest24 (Pliva-Lachema),
nevertheless the supplementary conventional biochemical tests
(acid production from arabinose, salicin, arbutin, hydrolysis
of aesculin) were done. Results were evaluated by software TNW
(Pliva-Lachema). Cellular fatty acid analysis was performed by
MIS Sherlock (MIDI, Inc., USA). Ribotyping of selected isolates
and reference cultures using EcoRI restriction enzyme and DNA
probe complementary to 16S and 23S rRNA was accomplished. From
138 aeromonads 35 A. hydrophila isolates were found.
Biochemical identification of isolates based on commercial kit
was often uncertain due to variations observed in some tests
and required additional testing. Among them, only one strain
from patient who probably acquired the infection in Egypt, was
identified as A. hydrophila ssp. dhakensis on the base of
ribotyping. All other isolates were identified as A. hydrophila
ssp. hydrophila, none of A. hydrophila ssp. ranae was proved.
Species identification was confirmed also by fatty acid
analysis. The less frequent A. hydrophila ssp. dhakensis was
occurred in our region. Use of an appropriate identification
approach can easily warn microbiologist of a rare species.
Diarrhoea due to A. hydrophila ssp. dhakensis was an imported
case of infection and ribotyping appeared to be a good tool for
the identification of aeromonads.
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Aeromonady patři mezi gramnegativni fermentujici oxidaza
pozitivni bakterie, ktere se vyskytuji běžně ve vodnich
ekosystemech tropů, subtropů i mirneho pasma. Tyto vodou
přenosne organismy mohou vsak u hostitele způsobovat take
gastroenteritidy, ale take ranne infekce ci vzacně zavažne
septicke stavy. Nejcastějsimi patogennimi aeromonadami clověka
jsou A. hydrophila subsp. hydrophila, A. caviae a A. sobria. Ve
vodnim prostředi se pak kromě zmiňovaných vyskytuji A.
bestiarum. A. salmonicida, A. media a dalsi. Biochemicke
vlastnosti skupiny 15 kmenů ziskaných z klinickeho materialu a
z vodniho prostředi byly testovany komercni soupravou
ENTEROtest24 (Pliva-Lachema) a dodatkovými testy.
Charakterizace kmenů byla rozsiřena ribotypizaci izolatů a
referencnich kmenů provedenou pomoci EcoRI restrikcniho enzymu
a znacene sondy komplementarni k 16S a 23S rRNA. Pomoci
biotypizace byly vsechny testovane kmeny identifikovany jako
zastupci A. hydrophila komplexu. Izolaty se shodovaly ve vsech
testech klicových pro A. hydrophila komplex a to bez ohledu na
zdroj izolatů. Ribotypizace umožnila zařazeni vsech klinických
izolatů až do poddruhu A. hydrophila subsp. hydrophila. Vodni
izolaty naleži do samostatne, od ostatnich kmenů dobře oddělene
skupiny. Jeden kmen teto skupiny vykazuje velkou podobnost
ribotypu s typovou kulturou A. bestiarum, zatimco ostatni kmeny
nebylo možne na zakladě podobnosti ribotypů klasifikovat. Z
výsledků vyplýva, že ackoliv byly vsechny kmeny na zakladě
shodných biochemických vlastnosti zařazeny do A. hydrophila
komplexu, ribotypizace odhalila zasadni rozdily v profilu
ribotypů izolatů z klinickeho materialu a z vodniho prostředi.
Testovane izolaty z vod pravděpodobně představuji nový taxon s
výjimkou jednoho A. bestiarum kmene. Ribotypizace narozdil od
biotypizace klasifikovala klinicke izolaty až do poddruhu a
jevi se být vhodnou metodou pro studium aeromonad. Přestože je
prace založena na male skupině kmenů potvrzuje se, že A.
hydrophila subsp. hydrophila je jednim z nejcetněji
zastoupených druhů aeromonad v klinickem materialu a že vodni
ekosystem je v zastoupeni aeromonad druhově rozmanitějsi.
Aeromonas spp. are known to do cause acute gastroenteritis.
Often predisposed are also very young children. We described
four cases of an acute watery diarrhoea due to aeromonads. All
children were up to one year old and by these patients
aeromonads were repeatedly isolated from stool samples. For two
of them hospital care was needed to improve their state of
health. Our findings should contribute to the knowledge, if
there is any link between such diarrhoea cases and the exact
Aeromonas species. Aeromonads were obtained from stool samples
during a routine survey in 2003 and 2004. Isolates were
identified by commercially available biochemical kit
ENTEROtest24 (Pliva-Lachema), conventional biochemical testing,
fatty acid analysis and ribotyping. In all used methods type
strains of all so far described species were included in the
study. Isolation of aeromonads were performed from two-week to
six-week period. In two cases of diarrhoea we identified A.
caviae species of which one was in consequence of one strain.
The strain identity was validated by ribotyping. A. caviae
isolates from the other case differed by production of acid
from cellobiose and salicin. The probable source of the
different A. caviae species infection was fresh water. From
remaining two gastroenteritis were identified A. veronii bv.
sobria/A. caviae and A. hydrophila ssp. hydrophila/A. caviae.
In the second case a likely source of infection were
grandparents of child who were suffered from diarrhoea after
homecoming from abroad. In both other mentioned cases stayed
the source of the infection unknown. Identification to the
species level was confirmed by ribotyping and fatty acid
analysis. Other enteric pathogens as Salmonella, Campylobacter
and Yersinia were not present in none of cases. Four cases of
small children suffering from an acute gastroenteritis proved,
that aeromonads can cause serious health problems, which are
not so rare. Whatever epidemiological circumstances are still
remaining unclear. We did not prove that this clinically
important cases were due to infection of one exact Aeromonas
species.
Out of the twenty-one A. hydrophila complex isolates obtained during a routine examination of human diarrhoeal faeces, two A. hydrophila subsp. dhakensis isolates (P1097 = CCM 7329 and P1165) were successfully identified by ribotyping. The correct taxonomic position of the A. hydrophila subsp. dhakensis CCM 7329 was verified by cpn60 sequencing (GeneBank accession number HM536193). The remaining A. hydrophila complex isolates were identified as A. hydrophila subsp. hydrophila. The ability of biochemical tests and fatty acid methyl ester analysis to reliably discern both A. hydrophila subsp. dhakensis and A. hydrophila subsp. hydrophila was limited. In contrast to the A. hydrophila subsp. hydrophila, the faecal isolates of A. hydrophila subsp. dhakensis did not produce acid from arbutin. When compared in a two-dimensional plot, the A. hydrophila subsp. dhakensis faecal isolates contained higher amounts of the two minor fatty acids C(13:0) and C(17:1) ω8c than the A. hydrophila subsp. hydrophila reference strain. This is the first detected occurrence of the less frequent A. hydrophila subsp. dhakensis in our region and ribotyping was proved as a suitable method for the identification of A. hydrophila subsp. dhakensis.
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